A DC/DC converter is an electronic device that converts a source of direct current (DC) from one voltage level to another. The converters are important in portable electronic devices such as cellular phones and laptop computers, which are supplied with power from batteries primarily.
Resonant converters comprised of interleaving multiple LLC circuits are widely used because they can improve power conversion efficiency and reduce the ripple on the output current of the converter. One exemplary interleaving LLC resonant converter disclosed in U.S. patent application Ser. Nos. 13/090,925 and 12/394,571 to which the present application claims priority includes two LLC resonant converters of a same architecture with their inputs electrically series-connected and their outputs electrically parallel-connected so as to make them share a same input voltage source, and supply a same output load. For such a converter, a current balance among the LLC resonant converters can be achieved by automatically adjusting input voltages of the LLC resonant converters while keeping the switching frequencies of the LLC resonant converters the same. However, under certain operation conditions, there may be imbalance between the input voltages of the two LLC resonant converters, i.e., one input voltage is very high while the other is very low, which makes voltage ratings of components for one LLC resonant converter too high, thereby affecting the normal operation of the LLC resonant converter.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.